The following correction was printed in the Guardian's Corrections and clarifications column, Saturday November 25

The past tense of strive is strove and not strived, as we had it in the standfirst to this article.

He hasn't changed. A few years ago, Conrad Black was denouncing journalists as drunken spongers, and his own investors as a "bunch of self-righteous hypocrites and ingrates". In a splendidly characteristic phrase he offered them no compromise: "I'm not prepared to re-enact the French revolutionary renunciation of the rights of nobility." And he now sarcastically calls a hostile biography of him "a heart-warming story of two sleazy, spivvy, contemptible people who enjoyed a fraudulent and unjust elevation".

When I read that I realised that I missed Lord Black of Crossharbour, and Lady Black, Barbara Amiel, as well. There was nothing quite like them before their vivid sojourn in London, and there has been nothing quite like them since, a couple who seemed to have stepped from the pages of Thackeray or Trollope; Becky Sharp meets Melmotte, perhaps.

And yet, for all the scandalmongering, the comedy of their social career, and Amiel's ill-advised boasting - "I have an extravagance that knows no bounds" - the most important thing about them is political. They made the one serious attempt to introduce American neoconservatism to this country. The Conservative party and the Tory press have not yet dealt with the residue.

It's said that the Blacks are bitter about the way those who once accepted their hospitality, and salary cheques, have turned on them, and I can't say I entirely blame them. Since I was never on the staff (although I wrote for both the Daily and Sunday Telegraph for a brief and not very happy period), and since my invitations to the Blacks' famously lavish parties all went astray in the post, I hope I can be acquitted of such ingratitude.

In any case, and whatever the American courts may decide that Black got up to with the petty cash, it's worth saying he wasn't a bad owner. There have been worse press proprietors; there are worse. Even if Black sometimes played the school bully, he never told his editors what to say, or censored his columnists.

At the same time, although he didn't claim, like his fellow-Canadian Beaverbrook, that he ran his papers for propaganda purposes alone, he tried to make himself the patron of the neoconservative movement. He became chairman of the National Interest, the Washington bimonthly that is the neocons' intellectual epicentre.

In the spirit of "plus royaliste ...", the Blacks' ferocious attachment to the true cause of American neoconservatism was all the stronger for their being Canadian, like their friends David "axis of evil" Frum and Mark Steyn. For some reason, Steyn no longer writes for the Telegraphs and Spectator as he used to, pronouncing from New Hampshire with enviable self-confidence on the affairs of Iraq or anywhere else.

Apart from predicting that George Bush would win the 2000 presidential election in a landslide, Steyn said at regular intervals that Osama bin Laden "will remain dead". Weeks after the invasion of Iraq he assured his readers that there would be "no widespread resentment at or resistance of the western military presence"; in December 2003 he wrote that "another six weeks of insurgency sounds about right, after which it will peter out"; and the following March he insisted that: "I don't think it's possible for anyone who looks at Iraq honestly to see it as anything other than a success story." I miss him, too.

My own dealings with the famous couple were slight but illuminating. At the end of one disagreeable evening - Peregrine Worsthorne's farewell dinner from the Sunday Telegraph - I stood on the staircase of London's Garrick Club while Black gave me a few minutes of quite well-reasoned abuse of one of my books. Then there was a party in 1994, at a time when I was writing another book, later published as The Controversy of Zion, which, though no bestseller, was generously received, as they say.

But no warm anticipation came from Amiel. Fixing me with a minatory glint of a smile, she said, "Your book on Zionism will be very interesting, Geoffrey, if you get it right." For a moment I thought she was going to add, "And we have ways of making you get it right."

What she meant by "right" could easily be seen from her columns in the Daily Telegraph. Perhaps because of her position as the proprietor's wife, she wrote with a refreshing lack of restraint. The very headlines of her pieces are exhilarating: "The UN is fast becoming a threat to world peace ... British journalists just don't understand the American way ... 'No more Mr Nice Guy': the lesson America has learnt ... Truth about Israeli casualties is being ignored in this war ... Anti-Americans are really against liberal democracy ... Why has it taken Le Pen to ask the awkward questions? ... Why I feel for these women catapulted into the high life."

In what was perhaps the most memorable of all her columns, Amiel said that an Israeli leader might soon "conclude that the dream of an Israeli homeland is finished and the Israelis will not get out alive. If so, he might further conclude that if we Jews cannot have the sliver of land for which we never wished to hurt anyone, if we must be pushed into the sea either literally or by demographics and attrition, we owe it to the memory of our forefathers to extract the highest price and not to go alone." Those words would scarcely need twisting or misreading to sound something like incitement to mass murder, and you don't get that every day in the mainstream press.

Not that it was wanted by many Telegraph readers. What always struck me was how dissonant such views must have seemed to ordinary English Tories. They aren't like that at all; not ideological, not fanatical, not even very pro-American or keen on the Iraq war. So David Cameron has noticed, even if the new owners and editors of the Telegraphs haven't.

It is not true that - as Amiel and some of our own Anglo-neocons like to complain - the British "establishment" is innately anti-American, but it is perfectly true that the Iraq war was hugely unpopular with Tory voters. For that matter, most British people thought that the Israeli action in Lebanon last summer was unjustified, and that went for right as well as left.

In Lady Black's days of glory, I used to wonder what the average Telegraph reader made of her lament that "it is too late to kill Arafat", and her belief that "this conflict in the Middle East is not amenable to a peaceful solution and can only be solved by the total victory of one side". Would any other writer on the Telegraph papers - even Charles Moore, Matthew d'Ancona or Simon Heffer - now endorse that, or her view that the Israelis would soon be "forced to use every means, not excluding nuclear power, to defend themselves"? Would the Conservative party?

When Black arrived in this country 20 years ago, few people knew much about the neoconservative doctrine, still less guessed to what disaster and humiliation it might lead in the deserts of Iraq. As he now awaits his day in court, Black says, with his usual gift for a phrase: "I have settled into my new life as a freedom fighter." It might be time for the Tories to fight for this country's freedom, from the consequences of the ideology he tried to import.

· Geoffrey Wheatcroft is the author of The Strange Death of Tory England